Figure 8. Identification of Klf2 as a repressor acting downstream of Bcl-6 regulating major T_FH genes.

a, Schematic of the CRISPR/Cas9-mediated gene knockdown of SMARTA cell system used for testing Klf2 in LCMV_Arm infection. wild-type or Bcl6^f/fPrdm1^f/f Cre^CD4 SMARTA CD4⁺ T cells transfected with crCd8 or crKlf2 were transferred to C57BL/6 host mice, followed by infection of the host mice with LCMV_Arm, and analyzed 6–7 days later. See Fig.8b–c and Extended Data Fig.9a,b.

b, Representative flow cytometry of T_FH and GC-T_FH cells, gated on SMARTA cells from spleens of LCMV_Arm infected mice in a. Three independent experiments were performed; each dot represents one mouse (n = 4). Data are mean ± s.d., unpaired two-tailed Student’s t-test.

c, Quantification of GC-T_FH core signature markers, gated on SMARTA cells from spleens of LCMV_Arm infected mice in a. CD44^lo naive CD4⁺ T cells were used as a negative control.

d,e, wild-type or Bcl6^f/fPrdm1^f/f Cre^CD4 SMARTA CD4⁺ T cells transfected with crCd8 or crKlf2 were transferred to C57BL/6 host mice, followed by immunization of the host mice with KLH-gp₆₁ and alum + cGAMP, and analyzed 8 days later. Representative flow cytometry and quantification of gp₆₆-restimulated IL-21⁺ and IL-4⁺ SMARTA cells from dLNs of KLH-gp₆₁ immunized mice. Two independent experiments were performed; each dot represents one mouse (n = 5). Data are mean ± s.d., unpaired two-tailed Student’s t-test. See Extended Data Fig.9d for experimental design.

f, Quantification of expression of Tcf-1, GATA-3, and Maf, gated on SMARTA cells from dLNs of KLH-gp₆₁ immunized mice in Extended Data Fig.9d.

g, A circuitry model of the regulation of T_FH genes upregulated by Bcl-6 through repression of repressor TFs.